Composition and a method of making and use of such composition

ABSTRACT

A composition and method of making such a composition that has application in the hydroprocessing of hydrocarbon feedstocks. The method comprises selecting an organic additive by the use of a correlation model for predicting catalytic activity as a function of a physical property that is associated with the organic additive and incorporating the organic additive into a support material to provide the additive impregnated composition.

This application is a divisional of U.S. application Ser. No. 13/367,935filed Feb. 7, 2012, which is incorporated herein by reference.

This invention relates to a composition that is impregnated with anorganic additive that is selected by utilizing a correlation model, amethod of making such a composition, and its use in the catalytichydroprocessing of hydrocarbon feedstocks.

With the increasingly more stringent requirements for reducing thelevels of sulfur and nitrogen contained in petroleum derived hydrocarbonproduct streams there has been an ongoing effort to find new or improvedhydroprocessing catalyst formulations and products that may suitably beused to more economically provide for the required sulfur and nitrogenreductions in the hydroprocessing of such petroleum derived hydrocarbonstreams.

Typical hydroprocessing catalysts known in the art can include a GroupVI metal (Mo and/or W) and a Group VIII (Co and/or Ni) as activecomponents which are supported on an inorganic oxide support material.These catalyst components may be combined and treated in a manydifferent ways to give catalyst compositions having certain desiredproperties.

Disclosed in the art are certain hydrotreating catalyst compositionsthat have incorporated in them various types of organic additivecompounds used for the purpose of improving the hydrogenation catalyticactivity of the compositions. Examples of such compositions aredisclosed in U.S. Pat. No. 7,235,173. This patent discloses ahydrotreating catalyst containing a group VIB and/or a group VIII metalwith an organic compound as an additive. The organic additive is acompound that contains at least one nitrogen atom and corresponds to aspecifically defined generic formula.

The catalyst of the '173 patent is prepared by incorporating thehydrogenation metals into a matrix material, such as by ion exchange ordry impregnation of the substrate followed by a calcination. The organiccompound may be introduced into the catalyst composition by dryimpregnation or by co-impregnation simultaneously with the metals or itmay be present in the sulfurization feedstock. The '173 patent indicatesthat its catalysts which employ the particular organic additive exhibitimproved activity over the comparative catalysts that do not employ anadditive.

A disadvantage with some of the disclosed methods of making catalystcompositions which contain certain activity enhancing additives is thatthere is no real approach to selecting the appropriate additive to useexcept by trial and error. Also, often the groups of additive compoundsdisclosed in the art as having possible use in the preparation ofhydroprocessing catalysts is so large that it is very difficult if notimpossible to make a good selection from the group of a proper additiveto use in the preparation of a catalyst.

It is, thus, an objective of the invention to provide a method of makingan additive-containing composition that is particularly suitable for usein the hydroprocessing of hydrocarbon feedstocks.

Another objective of the invention is to provide a method of making anadditive-containing composition, which method includes selecting from agroup of organic compounds an additive that may provide for a highactivity catalyst composition.

Accordingly, provided is method of making a composition, wherein saidmethod comprises: providing a support material; selecting an organicadditive from a group of organic additives, wherein said organicadditive has a complexation energy and is used for incorporation thereofinto said support material in the preparation of said composition thatprovides for a high activity catalyst composition, and wherein saidselecting of said organic additive from said group is done by utilizinga correlation model for estimating a predicted catalytic activity forsaid high activity catalyst composition as a function of a physicalproperty associated with each of said organic additive of said group;and incorporating said organic additive into said support material toprovide said support material having incorporated therein said organicadditive to thereby provide an additive-impregnated composition.

FIG. 1 presents plots of the relative volumetric activities (RVA) ofvarious catalyst compositions, each of which was prepared by theincorporation therein of a separately selected testing additive, as afunction of the characteristic complexation energy of each of theseparately selected testing additives used in the preparation of thevarious catalyst compositions, and presented is a statistic fit of thedata set.

The composition of the invention is particularly useful in applicationsinvolving the catalytic hydroprocessing of petroleum derived feedstocks,such as in the hydrotreating of atmospheric distillates, gas oils andresidues and of vacuum gas oils and residues.

One embodiment of the inventive composition is a hydroprocessingcatalyst composition that comprises a metals-incorporated shaped supportand an organic additive selected from the group consisting of aminecompounds having complexation energies of an absolute value of greaterthan 490 kcal/mol.

The metals-incorporated shaped support can comprise a porous refractoryoxide and a hydrogenation metal component selected from Group 6 of theIUPAC Periodic Table of the elements (e.g., chromium (Cr), molybdenum(Mo), and tungsten (W)) and Groups 9 and 10 of the IUPAC Periodic Tableof the Elements (e.g., cobalt (Co) and nickel (Ni)). Phosphorous (P) mayalso be a desired metal component.

In another embodiment, the inventive composition comprises a supportmaterial having incorporated therein a metal component and an organicadditive. A correlation model can be and is preferably used to selectthe organic additive that is incorporated into the composition. Thecorrelation model provides for estimating a predicted catalytic activityof a catalyst composition containing the organic additive as a functionof a selected physical property, such as complexation energy, of theorganic additive.

The support material used in the preparation of the inventive catalystcomposition may be any material that can suitably provide for thesupport of the metal hydrogenation components of the catalystcomposition and which has porosity that may further be filled with theorganic additive of the invention.

A porous refractory oxide is typically used as a support materialcomponent of a support material. Examples of possible suitable porousrefractory oxides include silica, alumina, titania, zirconia,silica-alumina, silica-titania, silica-zirconia, titania-alumina,zirconia-alumina, silica-titania and combinations of two or morethereof. The preferred porous refractory oxide for use in thepreparation of the support material of the composition of the inventionis one selected from the group consisting of alumina, silica, andsilica-alumina. Among these, the most preferred porous refractory oxideis alumina.

The porous refractory oxide generally may have an average pore diameterin the range of from about 50 Angstroms to about 200 Angstroms. Thetotal pore volume of the porous refractory oxide as measured by standardmercury porosimetry methods is in the range of from about 0.2 cc/gram toabout 2 cc/gram. The surface area of the porous refractory oxide, asmeasured by the B.E.T. method, generally exceeds about 100 m²/gram, andit is typically in the range of from about 100 to about 400 m²/gram.

The support or support material may be a shaped support comprising theporous refractory oxide that is prepared by any suitable method known tothose skilled in the art. Typically, in the preparation of a shapedsupport the porous refractory oxide starting material is in the form ofa powder and is mixed with water, and, if desired or necessary, otherchemical aids such as peptizing agents or flocculating agents or bindersor other compounds, to form a mixture or paste that may be formed intoan agglomerate or shaped particle.

It can be desirable to extrude the mixture to form extrudates of any oneor more of various shapes such as cylinders, trilobes, etc. havingnominal sizes such as 1/16 inch, ⅛ inch, 3/16 inch, and etc. Theagglomerate or shaped particle that comprises one or more of thepreviously listed inorganic oxide compounds is then dried and calcinedto give the final shaped support particle used in the preparation of theinventive catalyst composition.

The shaped support particle is dried under standard drying conditionsthat can include a drying temperature in the range of from 50° C. to200° C., preferably, from 75° C. to 175° C., and more preferably, from90° C. to 150° C.

After drying, the shaped support particle is calcined under standardcalcination conditions that include a calcination temperature in therange of from 250° C. to 900° C., preferably, from 300° C. to 800° C.,and, most preferably, from 350° C. to 600° C.

The shaped support that has been calcined should have a surface area andpore volume that allow for the impregnation of the shaped support withthe metal components and organic additive of the invention. The calcinedshaped support can have a surface area (determined by the BET methodemploying N₂, ASTM test method D3037) that is in the range of from 50m²/g to 450 m²/g, preferably, from 75 m²/g to 400 m²/g, and, mostpreferably, from 100 m²/g to 350 m²/g.

The mean pore diameter in angstroms (Å) of the calcined shaped supportis in the range of from 50 to 200, preferably, from 70 to 150, and, mostpreferably, from 75 to 125.

The pore volume of the calcined shaped support should exceed 0.55 cc/gand is typically in the range of from 0.5 cc/g to 1.1 cc/g. Moretypically, the pore volume is in the range of from 0.6 cc/g to 1.0 cc/g,and, most typically, it is from 0.7 to 0.9 cc/g. Less than ten percent(10%) of the total pore volume of the calcined shaped particle iscontained in the pores having a pore diameter greater than 350 Å,preferably, less than 7.5% of the total pore volume of the calcinedshaped particle is contained in the pores having a pore diameter greaterthan 350 Å, and, most preferably, less than 5%.

The references herein to pore size distribution and pore volume of thecalcined shaped particle are to those properties as determined bymercury intrusion porosimetry, ASTM test method D 4284. The measurementof the pore size distribution of the calcined shaped particle is by anysuitable measurement instrument using a contact angle of 140° with amercury surface tension of 474 dyne/cm at 25° C.

In a preferred embodiment of the invention, the shaped support particle,which preferably has been calcined, is impregnated in one or moreimpregnation steps with at least one metal component using one or moreaqueous solutions containing at least one metal salt wherein the metalcompound of the metal salt solution is an active metal or active metalprecursor. The metal elements are those selected from Group 6 of theIUPAC Periodic Table of the elements (e.g., chromium (Cr), molybdenum(Mo), and tungsten (W)) and Groups 9 and 10 of the IUPAC Periodic Tableof the Elements (e.g., cobalt (Co) and nickel (Ni)). Phosphorous (P) mayalso be a desired metal component.

For the Group 9 and 10 metals, the metal salts include Group 9 or 10metal acetates, formats, citrates, oxides, hydroxides, carbonates,nitrates, sulfates, and two or more thereof. The preferred metal saltsare metal nitrates, for example, such as nitrates of nickel or cobalt,or both.

For the Group 6 metals, the metal salts include Group 6 metal oxides orsulfides. Preferred are salts containing the Group 6 metal and ammoniumion, such as ammonium heptamolybdate and ammonium dimolybdate.

The concentration of the metal compounds in the impregnation solution(metal-containing solution) is selected so as to provide the desiredmetal content in the final composition of the invention taking intoconsideration the pore volume of the support material into which theaqueous solution is to be impregnated. Typically, the concentration ofmetal compound in the impregnation solution is in the range of from 0.01to 100 moles per liter.

The metal content of the shaped support having a metal componentincorporated therein may depend upon the application in which theadditive impregnated composition of the invention is to be used, but,generally, for hydroprocessing applications, the Group 9 and 10 metalcomponent, i.e., cobalt or nickel, preferably, nickel, can be present inthe support material having a metal component incorporated therein in anamount in the range of from 0.5 wt. % to 20 wt. %, preferably from 1 wt.% to 15 wt. %, and, most preferably, from 2 wt. % to 12 wt. %.

The Group 6 metal component, i.e., molybdenum or tungsten, preferably,molybdenum, can be incorporated into the shaped support in an amount inthe range of from 5 wt. % to 50 wt. %, preferably from 8 wt. % to 40 wt.%, and, most preferably, from 12 wt. % to 30 wt. %.

The above-referenced weight percents for the metal components are basedon the weight of the dry shaped support and the metal component as beingthe element regardless of the actual form, e.g., the oxide form orsulfide form, of the metal component.

In the inventive method of preparing or making the catalyst compositionof the invention, the metal-containing impregnation solution may be anaqueous solution comprising at least one metal, as described above,having a hydrogenation function. The at least one metal of themetal-containing impregnation solution may include, for example, a metalselected from the group consisting of nickel, cobalt, molybdenum,tungsten and any combination of two or more thereof, and is incorporatedinto the support material or shaped support to thereby provide ametal-incorporated support.

The incorporation of the metal-containing impregnation solution into thesupport material or shaped support may be done by any suitable means ormethod known to those skilled in the art. One such method may includestandard impregnation by incipient wetness or even soaking the supportmaterial or shaped support with an excess amount of the metal-containingimpregnation solution than would otherwise be used in a dry impregnationor an incipient wetness impregnation.

The metal-incorporated support undergoes a drying step by which at leasta portion of the volatiles content is driven from the metal-incorporatedsupport but leaving the metals behind upon the surface of the supportmaterial. The removal of at least a portion of the volatiles from themetal-incorporated support opens up pore volume which in a laterpreparation step is filled with an organic additive. Themetal-incorporated support, thus, is dried under drying conditions thatinclude a drying temperature.

In one embodiment of the inventive method, the drying temperature may beless than a calcination temperature. In this embodiment, the dryingtemperature under which the step of drying the metal-incorporatedsupport is conducted does not exceed a calcination temperature. Thus,the drying temperature should not exceed 400° C., and, preferably, thedrying temperature at which the metal-incorporated support is dried doesnot exceed 300° C., and, most preferably, the drying temperature doesnot exceed 250° C.

The drying of the metal-incorporated support may also be controlled in amanner so as to provide the resulting dried metal-incorporated supportthat has a volatiles content in a particular range. The volatilescontent of the dried metal-incorporated support should, in this case, becontrolled so that it does not exceed 20 wt. % LOI. It is preferred forthe LOI of the dried metal-incorporated support to be in the range offrom 1 wt. % to 20 wt. % LOI, and, more preferred, from 3 wt. % to 15wt. % LOI.

LOI, or loss on ignition, is defined as the percentage weight loss ofthe material after its exposure to air at a temperature of 482° C. for aperiod of two hours. LOI can be represented by the following formula:(sample weight before exposure less sample weight after exposure)multiplied by 100 and divided by (sample weight before exposure).

To provide the additive impregnated composition, the organic additive ofthe invention is incorporated into the support material by filling asignificant portion and up to the available pore volume of the pores ofthe support material with the organic additive. This is done by usingany suitable method or means to impregnate or incorporate the supportmaterial with the organic additive. In a preferred method, the supportmaterial is filled with organic additive by any of the standardwell-known pore fill methodologies whereby the pore volume is filled bytaking advantage of capillary action to draw liquid into the pores ofthe support material. It is desirable to fill at least 75% of theavailable pore volume of the support material with the organic additive,and, preferably, at least 80% of the available pore volume is filledwith the organic additive. Most preferably, at least 90% of theavailable pore volume of the support material is filled with the polaradditive.

An important feature of certain embodiments of the invention is the useof a correlation model in the selection of the organic additive that isincorporated into the support material and used in the preparation ofthe additive impregnated composition. The correlation model provides foran estimation of a predicted catalytic activity for a high activitycatalyst composition as a function of a physical property that may beused to characteristize the impregnated polar additive. One particularphysical property that has been found to correlate well with catalyticactivity is the complexation energy of organic additives. It isunderstood, however, that other physical properties may be used as wellto generate the correlation model.

One method of generating the correlation model of the invention includespreparing a plurality of additive impregnated compositions that are tobe tested, e.g., testing catalyst compositions, to determine theircatalytic activity. Each of the testing catalyst compositions is to beprepared using a separate or different organic additive from those ofthe other testing catalyst compositions. Each of the organic additivesmay be characterized by its own unique value for one of itscharacteristic physical properties, such as its complexation energy.

The catalytic activity of each of the testing catalyst compositions isthen measured using any suitable means or method known to those skilledin the art for testing or determining the activity of a catalystcomposition. In a preferred embodiment of the invention, thehydrodesulfurization activity of each of the testing catalystcompositions is measured.

The measurement of the activity of each of the testing catalystcompositions provides for the generation of a data set that includes thecatalytic activity of each of the testing catalyst compositions versus avalue representative of a particular physical property of the organicadditive that is impregnated into the given testing catalystcomposition. With this data set, a correlation model of the catalyticactivity and the physical property characteristic is generated. Thiscorrelation model can provide for estimating a predicted catalyticactivity of a high activity catalyst composition as a function of aphysical property of organic additives, and it can provide for theefficient selection of appropriate organic additives for use in themanufacture of additive impregnated and high activity catalystcompositions.

The organic additive that may be used in the preparation of the additiveimpregnated composition of the invention can be any suitable moleculethat provides for the desired catalytic benefits and enhancements as aredescribed herein. It has been discovered that one physicalcharacteristic that is predictive of or correlatable with the catalyticeffect of the organic compounds to be used as an impregnation additiveof hydrodesulfurization catalysts that comprise one or morehydrogenation metals supported on alumina is the complexation energy ofthe organic additive.

It has been found that complexation energy of an organic additive tendsto correlate well with the hydrodesulfurization catalytic activity ofthe additive-impregnated composition. The complexation energy of acompound, as the term is understood to mean in this specification, isthe enthalpy of reaction of a metal complex that includes a metalcation, such as a nickel cation or a cobalt cation, and a ligand.

To illustrate complexation energy, as the term is used in thisspecification, reference is made to the organic additive,ethylenediamine, which may form a complex with a nickel cation. In thisexample, the enthalpy of reaction, or complexation energy, may berepresented as the total energy of the metal complex,[(Ni(C₂H₄(NH₂)₂)₃]²⁺, less the total energy of the nickel cation,[Ni]²⁺, and of the ligands, [C₂H₄(NH₂)₂)], of the complex.

A desirable feature of the organic additive of the invention is for itto be capable of forming with a transition metal, such as nickel orcobalt, a metal complex. Therefore, the molecular structure of theorganic additive should, preferably, provide for binding with a metalcation of either nickel or cobalt to form a metal complex.

Examples of classes of compounds from which the organic additive of theinvention may be selected include amide (including formamide) compounds,amine compounds, nitrile compounds, pyrrolidone compounds, ureacompounds, and oxalate compounds. Among these compounds the preferredclasses of compounds from which the organic additive is selected areamine compounds, amide compounds and oxalate compounds.

The preferred amine compounds include long chain amines, includingprimary, secondary, and tertiary amines, and those containing from onecarbon to 20 carbons, with the carbon chains being either staturated orunsaturated. One particularly preferred amine compound that may be usedas an organic additive of the invention is octylamine.

The preferred amide compounds include those of the formamide series offormamide, methylformamide, dimethylformamide and diethylformamide.Among these, particularly beneficial formamide compounds includediethylformamide and dimethylformamide.

As already noted, the complexation energy of the organic additive may beused as an indicator of the catalytic benefit that can be provided bythe organic additive when it is used as a component of the catalystcomposition of the invention. It has been found that for certain organiccompounds, which may act or function as a ligand in the formation of atransition metal complex, the catalytic activity of an additiveimpregnated composition used in the hydrotreatment of hydrocarbonfeedstocks increases with increases in the complexation energy of theorganic additive.

To provide for a minimum level of catalytic benefit, the organicadditive selected for use in the additive impregnated composition of theinvention ought to have a complexation energy of an absolute value ofgreater than 470 kcal/mol. It preferred for the organic additive to havea complexation energy of an absolute value of greater than 490 kcal/mol,and more preferred, the complexation energy can have an absolute valueof greater than 500 kcal/mol.

The complexation energy of an organic additive may be determined bycalculation using the publicly available, under license, computersoftware program named Materials Studio, version 4.4, copyright December2008, distributed by Accelrys Inc. (Accelrys, Inc. 10188 Telesis Court,Suite 100, San Diego, Calif. 92121, USA), or the complexation energy maybe determined by any other method recognized by those skilled in the artfor calculating the complexation energy of a ligand compound and whichsuch method will provide values for complexation energy that approximatethose generated by the use of the Materials Studio software.

Following is a brief discussion of some of the technical principlesbehind the computation method and the application of the MaterialsStudio computer software program used for calculating complexationenergy of an organic additive compound. The total energy of the metalcomplex, metal cation and ligand that form a complex is calculated fromfirst principles using density functional theory as implemented in thecomputer modeling code DMol³. DMol³ (B. Delley, J. Phys. Chem. A 110(2006) 13632) is one of the Materials Studio software codes. To use thismodel, the parameters needed to perform the calculations within theDMol³ program are first selected.

The NLSD functional BLYP, consisting of the Becke exchange functional(B88) and the Lee-Yang-Parr correlation functional, are used. To obtainthe electronic groundstate of the complex, a spin-unrestricted formulismis employed with the formal charges being used to set the initial spinsof the atomic centers. The net charge of the complex is set to 2+ tocoincide with the oxidation state of the nickel cation. A full geometryoptimization of the model structures is performed using the mediumsetting for the quality of the convergence criteria. Medium settings areused to specify the criteria for the orbital cutoffs, the convergencecriteria for the self-consistent field (SCF) calculation, and theprecision used in the numerical integration of the Hamiltonian. Finally,an effective core potential (ECP) basis set is used at the doublenumerical with polarization functions (DNP) level of accuracy. With theselection of the above described parameters, the Materials Studiosoftware may be run to generate complexation energy of the give organicadditive.

The additive-impregnated composition of the invention may be treated,either ex situ or in situ, with hydrogen and with a sulfur compound. Oneof the beneficial features of the invention is that a non-sulfurizedcomposition may be loaded into a reactor in which it can be activated,in situ, by a hydrogen treatment step followed by a sulfurization step.

The hydrogen treatment includes exposing the additive-impregnatedcomposition to a gaseous atmosphere containing hydrogen at a temperatureranging upwardly to 250° C. Preferably, the additive-impregnatedcomposition is exposed to the hydrogen gas at a hydrogen treatmenttemperature in the range of from 100° C. to 225° C., and, mostpreferably, the hydrogen treatment temperature is in the range of from125° C. to 200° C.

The partial pressure of the hydrogen of the gaseous atmosphere used inthe hydrogen treatment step generally can be in the range of from 1 barto 70 bar, preferably, from 1.5 bar to 55 bar, and, most preferably,from 2 bar to 35 bar.

The additive impregnated-composition is contacted with the gaseousatmosphere at the aforementioned temperature and pressure conditions fora hydrogen treatment time period in the range of from 0.1 hours to 100hours, and, preferably, the hydrogen treatment time period is from 1hour to 50 hours, and most preferably, from 2 hours to 30 hours.

Sulfiding of the additive-impregnated composition after it has beentreated with hydrogen can be done using any conventional method known tothose skilled in the art. Thus, the hydrogen treatedadditive-impregnated composition can be contacted with asulfur-containing compound, which can be hydrogen sulfide or a compoundthat is decomposable into hydrogen sulfide, under the contactingconditions of the invention.

Examples of such decomposable compounds include mercaptans, CS₂,thiophenes, dimethyl sulfide (DMS), and dimethyl disulfide (DMDS). Also,preferably, the sulfiding is accomplished by contacting thehydrogen-treated composition, under suitable sulfurization treatmentconditions, with a hydrocarbon feedstock that contains a concentrationof a sulfur compound. The sulfur compound of the hydrocarbon feedstockcan be an organic sulfur compound, particularly, one which is typicallycontained in petroleum distillates that are processed byhydrodesulfurization methods.

Suitable sulfurization treatment conditions are those which provide forthe conversion of the active metal components of the hydrogen-treated,additive-impregnated composition to their sulfided form. Typically, thesulfiding temperature at which the hydrogen treated additive impregnatedcomposition is contacted with the sulfur compound is in the range offrom 150° C. to 450° C., preferably, from 175° C. to 425° C., and, mostpreferably, from 200° C. to 400° C.

When using a hydrocarbon feedstock that is to be hydrotreated using thecatalyst composition of the invention to sulfide the hydrogen treatedcomposition, the sulfurization conditions can be the same as the processconditions under which the hydrotreating is performed. The sulfidingpressure at which the hydrogen treated additive impregnated compositionis sulfided generally can be in the range of from 1 bar to 70 bar,preferably, from 1.5 bar to 55 bar, and, most preferably, from 2 bar to35 bar.

One of the benefits provided by the additive impregnated composition ofthe invention is that it can be utilized in a reactor system that isstarted up using a so-called delayed feed introduction procedure. In thedelayed feed introduction procedure, the reactor system, which includesa reactor vessel containing the additive-impregnated composition, firstundergoes a heating step to raise the temperature of the reactor and theadditive-impregnated composition contained therein in preparation forthe introduction of a sulfiding agent or heated hydrocarbon feedstockfor processing. This heating step includes introducing into the reactorthe hydrogen-containing gas at the aforementioned hydrogen treatmentconditions. After the hydrogen treatment of the additive-impregnatedcomposition, it is thereafter treated with a sulfur compound in themanner as earlier described herein.

It is recognized that the additive impregnated composition of theinvention, after its treatment with hydrogen and sulfur, is a highlyeffective catalyst for use in the hydrotreating of hydrocarbonfeedstocks. This catalyst is particularly useful in applicationsinvolving the hydrodesulfurization of hydrocarbon feedstocks, and,especially, it has been found to be an excellent catalyst for use in thehydrodesulfurization of distillate feedstocks, in particular, diesel, tomake an ultra-low sulfur distillate product having a sulfurconcentration of less than 15 ppmw, preferably, less than 10 ppmw, and,most preferably, less than 8 ppmw.

In the hydrotreating applications, the additive impregnated composition,which is preferably used in a delayed feed introduction procedure orotherwise treated with hydrogen and sulfur, as described above, iscontacted under suitable hydrodesulfurization conditions with ahydrocarbon feedstock that typically has a concentration of sulfur.

The more typical and preferred hydrocarbon feedstock is a petroleummiddle distillate cut having a boiling temperature at atmosphericpressure in the range of from or about 140° C. to or about 410° C. Thesetemperatures are approximate initial and boiling temperatures of themiddle distillate.

Examples of refinery streams intended to be included within the meaningof middle distillate include straight run distillate fuels boiling inthe referenced boiling range, such as, kerosene, jet fuel, light dieseloil, heating oil, heavy diesel oil, and the cracked distillates, such asFCC cycle oil, coker gas oil, and hydrocracker distillates. Thepreferred feedstock of the inventive distillate hydrodesulfurizationprocess is a middle distillate boiling in the diesel boiling range offrom about 140° C. to 400° C.

The sulfur concentration of the middle distillate feedstock can be ahigh concentration, for instance, being in the range upwardly to about 2weight percent of the distillate feedstock based on the weight ofelemental sulfur and the total weight of the distillate feedstockinclusive of the sulfur compounds.

Typically, however, the distillate feedstock of the inventive processhas a sulfur concentration in the range of from 0.01 wt. % (100 ppmw) to1.8 wt. % (18,000). But, more typically, the sulfur concentration is inthe range of from 0.1 wt. % (1000 ppmw) to 1.6 wt. % (16,000 ppmw), and,most typically, from 0.18 wt. % (1800 ppmw) to 1.1 wt. % (11,000 ppmw).

It is understood that the references herein to the sulfur content of thedistillate feedstock are to those compounds that are normally found in adistillate feedstock or in the hydrodesulfurized distillate product andare chemical compounds that contain a sulfur atom and which generallyinclude organosulfur compounds.

The additive impregnated composition of the invention may be employed asa part of any suitable reactor system that provides for contacting it orits derivatives with the distillate feedstock under suitablehydrodesulfurization conditions that may include the presence ofhydrogen and an elevated total pressure and temperature.

Such suitable reaction systems can include fixed catalyst bed systems,ebullating catalyst bed systems, slurried catalyst systems, andfluidized catalyst bed systems.

The preferred reactor system is that which includes a fixed bed of theinventive catalyst contained within a reactor vessel equipped with areactor feed inlet means, such as a feed nozzle, for introducing thedistillate feedstock into the reactor vessel, and a reactor effluentoutlet means, such as an effluent outlet nozzle, for withdrawing thereactor effluent or the treated hydrocarbon product or the ultra-lowsulfur distillate product from the reactor vessel.

The hydrodesulfurization process generally operates at ahydrodesulfurization reaction pressure in the range of from 689.5 kPa(100 psig) to 13,789 kPa (2000 psig), preferably from 1896 kPa (275psig) to 10,342 kPa (1500 psig), and, more preferably, from 2068.5 kPa(300 psig) to 8619 kPa (1250 psig).

The hydrodesulfurization reaction temperature is generally in the rangeof from 200° C. (392° F.) to 420° C. (788° F.), preferably, from 260° C.(500° F.) to 400° C. (752° F.), and, most preferably, from 320° C. (608°F.) to 380° C. (716° F.).

The flow rate at which the distillate feedstock is charged to thereaction zone of the inventive process is generally such as to provide aliquid hourly space velocity (LHSV) in the range of from 0.01 hr⁻¹ to 10hr⁻¹.

The term “liquid hourly space velocity”, as used herein, means thenumerical ratio of the rate at which the distillate feedstock is chargedto the reaction zone of the inventive process in volume per hour dividedby the volume of catalyst contained in the reaction zone to which thedistillate feedstock is charged.

The preferred LHSV is in the range of from 0.05 hr⁻¹ to 5 hr⁻¹, morepreferably, from 0.1 hr⁻¹ to 3 hr⁻¹ and, most preferably, from 0.2 hr⁻¹to 2 hr⁻¹.

It is preferred to charge hydrogen along with the distillate feedstockto the reaction zone of the inventive process. In this instance, thehydrogen is sometimes referred to as hydrogen treat gas. The hydrogentreat gas rate is the amount of hydrogen relative to the amount ofdistillate feedstock charged to the reaction zone and generally is inthe range upwardly to 1781 m³/m³ (10,000 SCF/bbl). It is preferred forthe treat gas rate to be in the range of from 89 m³/m³ (500 SCF/bbl) to1781 m³/m³ (10,000 SCF/bbl), more preferably, from 178 m³/m³ (1,000SCF/bbl) to 1602 m³/m³ (9,000 SCF/bbl), and, most preferably, from 356m³/m³ (2,000 SCF/bbl) to 1425 m³/m³ (8,000 SCF/bbl).

The desulfurized distillate product yielded from the process of theinvention has a low or reduced sulfur concentration relative to thedistillate feedstock. A particularly advantageous aspect of theinventive process is that it is capable of providing a deeplydesulfurized diesel product or an ultra-low sulfur diesel product. Asalready noted herein, the low sulfur distillate product can have asulfur concentration that is less than 50 ppmw or any of the other notedsulfur concentrations as described elsewhere herein (e.g., less than 15ppmw, or less than 10 ppmw, or less than 8 ppmw).

The following examples are presented to further illustrate certainaspects of the invention, but they are not to be construed as limitingthe scope of the invention.

EXAMPLE 1

This Example 1 describes the standard procedure used in the preparationof each of the catalyst compositions that was impregnated with aseparately selected organic additive each of which having acharacteristic complexation energy. Each of the catalyst compositionsimpregnated with its particular organic additive was tested as describedin Example 2 to determine its relative catalytic activity.

100 weight parts of 1.3 mm Trilobe extrudate alumina support wasimpregnated with an aqueous solution of molybdenum, cobalt, andphosphorous so as to provide a base catalyst composition that, afterdrying and calcination, contained 14.8 wt. % molybdenum, 4.2 wt. %cobalt, and 2.4 wt. % phosphorous, with the weight percents being basedon dry catalyst weight.

The impregnation solution used for incorporating the metal componentsinto the alumina support was prepared by mixing 33.4 weight partsmolybdenum trioxide (MoO₃), 10.1 weight parts cobalt hydroxide(Co(OH)₂), 13.3 weight parts phosphoric acid (H₃PO₄), and 100 weightparts deionized water. These mixed ingredients were heated toapproximately 93° C. (200° F.) in order to dissolve the components andprovide a clear liquid. The cooled solution was then further dilutedwith deionized water to provide the desired impregnation volume forimpregnating the extrudate alumina support.

After the impregnation of the alumina support with the metals solutionand its aging, the impregnated extrudate was dried and calcined toprovide the base catalyst composition to be impregnated with the organicadditive.

A plurality of catalyst compositions were prepared for testing each byimpregnating an aliquot portion of the base catalyst with one of theselected testing additives (organic additives) listed in the followingTable 1 in an amount such as to have filled 90% of the pore volume ofthe aliquot portion of the base catalyst. The additive-impregnatedcatalyst composition was then allowed to age at ambient temperaturebefore loading into a testing reactor for testing and measuringcatalytic performance as described in Example 2.

TABLE 1 Selected Physical Properties, Including Complexation Energy, ofOrganic Additives. Boiling Complexation Compound Formula Class Point (°C.) Energy (kcal/mol) Dimethylformamide C₃H₇NO Amide 153 −517.3n-methylpyrrolidone C₅H₉NO Cyclic-amide 202 −518.0 TetramethylureaC₅H₁₂N₂O Diamine 174-178 −503.4 Acetonitrile C₂H₃N Nitrile  82 −501.4Adiponitrile (CH₂)₄(CN)₂ dinitrile 295 −491.5 Triethylphosphate C₆H₁₅O₄PPhosphate 215-216 −481.2 Triethylphosphite C₆H₁₅O₃P Phosphite 156 −466.4Ethylenediamine C₂H₈N₂ Diamine 116 −485.6 Formamide CH₃NO Amide 210−492.2 Octylamine C₈H₁₉N Amine 175-176 −532.4 1-pentanol C₅H₁₂O Alcohol138 −469.0 Diethylformamide (CH₃)₂NC(O)H Amide 153 −532.7methylformamide CH₃NHCHO Amide 198-200 −517.3

EXAMPLE 2

This Example 2 describes the procedure for testing the catalyticactivity of each of the additive-impregnated catalyst compositionsdescribed in Example 1 to generate a data set of catalytic activityversus the complexation energy of the organic additive.

Trickle flow micro-reactors were used to test the hydrodesulfurizationactivity of additive-impregnated compositions. A 50 cc volume, based oncompacted bulk density of whole pellets, of each additive-impregnatedcomposition was used in the testing. The reactors were packed withextrudates of each composition, which were diluted with 80-60 mesh SiCin the volumetric composition-to-diluent ratio of 1:2.8. Thecompositions were conditioned and sulfided using a delayed-feedintroduction procedure whereby the composition was first heated up andconditioned by contacting it with pure hydrogen at the operatingpressure and at a temperature in the range of from 149° C. (300° F.) to204° C. (400° F.) for a time period of about 12 hours. Following thishydrogen treatment, the composition was sulfided using a liquidhydrocarbon containing sulfur spiking agent to provide a sulfur contentof 2.5%.

The activities (relative activities) of the additive-impregnatedcompositions were tested by charging the catalyst filled reactordescribed above with a straight run gas oil feedstock of a dieselboiling range having a sulfur content. The reactors were operated at apressure of 600 psig, at a rate so as to provide a liquid hourly spacevelocity (LHSV) of 1.0 hr⁻¹. The hydrogen gas rate charged to thereactor was 1200 scf H₂/bbl. The weight average bed temperature (WABT)was adjusted to a temperature in the range of 349° C. (660° F.) to 354°C. (670° F.).

Rate constants were determined for each of the additive-impregnatedcompositions assuming a reaction order of 1.3. The relative volumetricactivity (RVA) for each of the additive-impregnated compositions wasdetermined relative to the particular additive-impregnated compositioncontaining dimethyleformamide (DMF) using the formula:RVA=(K_(exp)/K_(ref))×100; where K_(exp) is the reaction ratecoefficient of the particular tested additive-impregnated composition,and K_(ref) is the reaction rate coefficient of the referenceadditive-impregnated composition, i.e., the DMF impregnated composition.

The RVA determined for each of the additive-impregnated compositions ispresented in the following Table 2.

TABLE 2 RVA of Additive-Impregnated Catalyst Compositions Compound RVADimethylformamide 1 n-methylpyrrolidone 1.05 Tetramethylurea 0.95Acetonitrile 0.825 Adiponitrile 0.845 Triethylphosphate 0.8Triethylphosphite 0.6 Ethylenediamine 0.7 Formamide 0.72 Octylamine 1.281-pentanol 0.7 Diethylformamide 1.14 Methylformamide 0.9

From the data set of RVA versus complexation energy a correlation modelwas generated. The correlation model was obtained by use of a partialleast squares (PLS) analysis of the data set. FIG. 1 presents theresults of the activity testing of the additive impregnated compositionsand the statistical fitting of the data set. There is clearly a closecorrelation between RVA of the additive-impregnated compositions and thecomplexation energies of the additives used in the preparation of theadditive-impregnated compositions.

That which is claimed is:
 1. A composition for use in thehydroprocessing of a hydrocarbon feedstock, wherein said compositioncomprises: a support material having incorporated therein a metalcomponent and an organic additive selected by the use of a correlationmodel, wherein said correlation model provides for estimating apredicted catalytic activity of said composition that has been preparedwith said organic additive having a characteristic complexation energy,and wherein said organic additive is selected from a group consisting ofamide compounds, amine compounds, nitrile compounds, pyrrolidonecompounds, urea compounds, and oxalate compounds, wherein said organicadditive is capable of forming a metal complex with a transition metal,and wherein said organic additive has said complexation energy of anabsolute value of greater than 470 kcal/mol.
 2. A composition as recitedin claim 1, wherein said metal component is selected from the group ofGroup 9 or Group 10 metals consisting of cobalt and nickel present insaid composition in an amount in the range of from 0.5 wt. % to 20 wt.%, and the group of Group 6 metals consisting of molybdenum and tungstenpresent in said composition in an amount in the range of from 5 wt. % to50 wt. %, wherein the weight percents are based on the weight of the drysupport material with the metal component as the elemental formregardless of its actual form.
 3. A composition as recited in claim 2,wherein said support material a porous refractory oxide selected fromthe group of refractory oxides consisting of silica, alumina, titania,zirconia, silica-alumina, silica-titania, silica-zirconia,titania-alumina, zirconia-alumina, silica-titania and combinations oftwo or more thereof; and wherein said support material has a surfacearea (as determined by the BET method) in the range of from 50 m2/g to450 m2/g, a mean pore diameter in the range of from 50 to 200 angstroms(Å), and a total pore volume exceeding 0.55 cc/g.
 4. A hydroprocessingprocess, comprising: contacting under hydroprocessing conditions thecomposition of any one of claims 1 through 3 with a hydrocarbonfeedstock.